US3380896A - High purification of phthalic anhydride by multi-stage reduced pressure distillation - Google Patents

High purification of phthalic anhydride by multi-stage reduced pressure distillation Download PDF

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Publication number
US3380896A
US3380896A US546807A US54680766A US3380896A US 3380896 A US3380896 A US 3380896A US 546807 A US546807 A US 546807A US 54680766 A US54680766 A US 54680766A US 3380896 A US3380896 A US 3380896A
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phthalic anhydride
column
pressure
product
distillation
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US546807A
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English (en)
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Scheiber Werner
Otto L Garkisch
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GEA Group AG
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Metallgesellschaft AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/54—Preparation of carboxylic acid anhydrides
    • C07C51/573—Separation; Purification; Stabilisation; Use of additives

Definitions

  • ABSTRACT OF THE DSCLOSURE A process which can be run continuously for the recovery of highly purified phthalic anhydride from an aged oxidation product of naphthalene or oxylene in which the resulting crude phthalic anhydride is first heated under pressure to vavoid evaporation of any of the phthalic anhydride, then subjected to an equilibrium evaporation distillation by a relief of pressure under super atmospheric pressure during which crude phthalic anhydride is distilled ofi and high boiling non-volatile impurities are continuously removed as a sump product, and then the distilled phthalic anhydride is treated in a multistage rectifier to remove volatile impurities and the phthalic anhydride is finally distilled under vacuum to remove high boilers formed in the rectifier.
  • This invention relates to recovering purified phthalic anhydride from the oxidation product of either naphthalene or O-Xylene employing selective distillation steps under reduced pressure particularly adapted to a continuous process.
  • Phthalic anhydride is presently recovered from the oxidation product of naphthalene or o-Xylene by batch distillation in a purity of 99.8%, which is required for further processing.
  • the distillation is usually carried out after an aging treatment, which is effected by a prolonged heating at Z50-280 C. under atmospheric pressure and, if desired, in the presence of sulfuric acid or other admixtures.
  • This aging serves to destroy impurities, such as monocarboxylic acids, aldehydes and quinones, or to transform them into nonvolatile components.
  • impurities such as monocarboxylic acids, aldehydes and quinones
  • the easily volatile impurities mainly maleic anhydride
  • the easily volatile impurities are initially distilled off in a distillation which succeeds the aging -treatment and is carried out with the aid of a still.
  • the main portion of the oxidation product is stripped off as purified phthalic anhydride and the condensation polymers formed during the preceding aging are removed from the still as a residue.
  • the batch operation is still quite economical.
  • the present invention relates to a process which enables recovery of phthalic anhydride of very high purity in a continuous distillation process. This high purity meets all previous requirements as well as the increased requirements to be expected in the future for phthalic anhydride.
  • the oxidation product of o-Xylene or the oxidation product of naphthalene may be used as a starting material.
  • the aging pretreatment which is known per se may be employed according to the starting material treated.
  • An essential feature of the invention is that at least a considerable part of the heat which is required for evaporating the crude phthalic anhydride is supplied to the latter as tangible heat before the crude phthalic anhydride is introduced into the distillation equipment and while said crude phthalic anhydride is maintained under a pressure which prevents virtually any evaporation of the crude phthalic anhydride during this preheating step. Then the crude phthalic anhydride is subjected to an equilibrium evaporation by a relief of pressure. This equilibrium evaporation is carried out under a superatmospheric pressure, suitably about 1GO-150 millimeters mercury absolute pressure.
  • this starting material is preheated only to about 280 C. so that only about 40% thereof is evaporated by fiashing whereas the additional amount of heat required for evaporating a total of about 97% of the feed is supplied by a sump boiler.
  • the prepurifred phthalic anhydride which has been distilled off in the flashing unit is then supplied to a multistage rectifying column, which is also operated under a vacuum and in which the readily volatile impurities, such as maleic anhydride, are distilled off.
  • the sump product, from which the readily volatile impurities have been removed is then subjected to simple equilibrium evaporation in a third column, which is also operated under vacuum, and is withdrawn as a head product.
  • This final distillation is only required to ensure that the very small traces of higher-boiling substances which have formed during the multistage rectification in the second column are removed from the end product so that it is normally not required to Withdraw the sump product from this final distillation column. I f higher-boiling impurities have increased in the sump of this final column after a long period of continuous operation, part of the sump product may be withdrawn from this column.
  • FIGURE 1 is a schematic diagram of a continuous process according to the invention in which very pure phthalic anhydride is recovered from an oxidation product of naphthalene
  • FIGURE 2 is a schematic diagram of a continuous process according to the invention in which Very pure phthalic anhydride is recovered from an oxidation product of o-xylene.
  • Example 1 The material which was available was a pre-aged oxidation product of hot-pressed naphthalene stock. This This feedstock was charged at 280 C. at a rate of 1000 kg. per hour through conduit 1 and heater 2 into the first column 3. The feedstock was heated to 450 C. in the heater. Except for a helix 4a, the flashing column 3 was empty. By means of the vacuum conduit 5, the column 3 was held at a pressure of 100 mm. mercury. The dephlegunator 6 was operated at a temperature of 203 to 205 C. so that virtually the entire head product was passed through column 7 into the ne fractionating column 8. The amount of product passed through line 7 wasabout 930 kg. per hour. Thus, there was only a spurious reux in the space between the inlet of conduit 1 and the dephlegmator 6. The bottom temperature in column 8 was maintained at 215 to 218 C.
  • Example 2 The material which was available was an oxidation product of a o-xylene and had a typical analysis as follows:
  • Phthalic acid content Cannot be detected.
  • Benzoic acid content Cannot be detected.
  • a process for recovering very pure phthalic anhydride from a starting material consisting of an oxidation product of naphthalene comprising in combination heating the starting material to about 450 C., subjecting the heated starting material to a pressure relief in a first distillation column operating at a pressure of about 100 millimeters of mercury absolute pressure, the heated starting material being the sole source of heating the rst distillation column,
  • head product phthalic anhydride which is at least 99.8% by weight pure.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Furan Compounds (AREA)
US546807A 1965-05-04 1966-05-02 High purification of phthalic anhydride by multi-stage reduced pressure distillation Expired - Lifetime US3380896A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEM65101A DE1295540B (de) 1965-05-04 1965-05-04 Verfahren zur Herstellung von reinstem Phthalsaeureanhydrid

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US3380896A true US3380896A (en) 1968-04-30

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US546807A Expired - Lifetime US3380896A (en) 1965-05-04 1966-05-02 High purification of phthalic anhydride by multi-stage reduced pressure distillation

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US (1) US3380896A (enrdf_load_stackoverflow)
JP (1) JPS548664B1 (enrdf_load_stackoverflow)
BE (1) BE680473A (enrdf_load_stackoverflow)
CS (1) CS150931B2 (enrdf_load_stackoverflow)
DE (1) DE1295540B (enrdf_load_stackoverflow)
GB (1) GB1121588A (enrdf_load_stackoverflow)
NL (1) NL6602053A (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3540987A (en) * 1967-07-07 1970-11-17 Metallgesellschaft Ag Purification of phthalic anhydride by batch distillation,accumulation and continuous distillation
US3655521A (en) * 1968-03-27 1972-04-11 Zieren Chemiebau Gmbh Dr A Pretreatment process for the distillation of crude phthalic anhydride
US3886050A (en) * 1968-08-02 1975-05-27 Chemie Linz Ag Process for the preparation of pure phthalic anhydride
JPS53137926A (en) * 1977-05-06 1978-12-01 Nippon Steel Chem Co Ltd Treatment of residue of distillation of phthalic anhydride
US4430163A (en) 1980-12-17 1984-02-07 Davy Mckee Aktiengesellschaft Process for the continuous separation of slightly volatile components from a crude phthalic acid anhydride
US5508443A (en) * 1994-05-12 1996-04-16 Exxon Chemical Patents Inc. Liquid phthalic anhydride recovery process
US5718808A (en) * 1996-11-29 1998-02-17 Exxon Chemical Patents Inc. Solvent assisted process for recovery of phthalic anhydride in the liquid phase by distillation
US5730844A (en) * 1996-11-29 1998-03-24 Exxon Chemical Patents Inc. Liquid phthalic anhydride recovery process using a rectification tower with benzoic acid control
US5869700A (en) * 1997-02-21 1999-02-09 Exxon Chemical Patents Inc. Method for recovering phthalic anhydride/maleic anhydride mixtures by distillation

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2670325A (en) * 1951-07-14 1954-02-23 American Cyanamid Co Distillation purification of phthalic anhydride
US2786805A (en) * 1954-03-01 1957-03-26 California Research Corp Process of purification of phthalic anhydride
US3011955A (en) * 1959-06-04 1961-12-05 Scient Design Co Purification of phthalic anhydride
US3135669A (en) * 1961-10-16 1964-06-02 Badger Co Purification of maleic anhydride by flash vaporization and two stage fractional distillation

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1181691B (de) * 1958-05-30 1964-11-19 Imp Exp Chemischer Anlagen Verfahren zur kontinuierlichen Destillation von Phthalsaeureanhydrid
DE1097427B (de) * 1959-08-14 1961-01-19 Basf Ag Verfahren zur Gewinnung von reinem Phthalsaeureanhydrid aus dem bei der Oxydation von Naphthalin erhaltenen Rohprodukt
DE1167810B (de) * 1960-11-12 1964-04-16 Basf Ag Verfahren zur Gewinnung von reinem Phthalsaeureanhydrid

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2670325A (en) * 1951-07-14 1954-02-23 American Cyanamid Co Distillation purification of phthalic anhydride
US2786805A (en) * 1954-03-01 1957-03-26 California Research Corp Process of purification of phthalic anhydride
US3011955A (en) * 1959-06-04 1961-12-05 Scient Design Co Purification of phthalic anhydride
US3135669A (en) * 1961-10-16 1964-06-02 Badger Co Purification of maleic anhydride by flash vaporization and two stage fractional distillation

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3540987A (en) * 1967-07-07 1970-11-17 Metallgesellschaft Ag Purification of phthalic anhydride by batch distillation,accumulation and continuous distillation
US3655521A (en) * 1968-03-27 1972-04-11 Zieren Chemiebau Gmbh Dr A Pretreatment process for the distillation of crude phthalic anhydride
US3886050A (en) * 1968-08-02 1975-05-27 Chemie Linz Ag Process for the preparation of pure phthalic anhydride
JPS53137926A (en) * 1977-05-06 1978-12-01 Nippon Steel Chem Co Ltd Treatment of residue of distillation of phthalic anhydride
US4430163A (en) 1980-12-17 1984-02-07 Davy Mckee Aktiengesellschaft Process for the continuous separation of slightly volatile components from a crude phthalic acid anhydride
US5508443A (en) * 1994-05-12 1996-04-16 Exxon Chemical Patents Inc. Liquid phthalic anhydride recovery process
US5731443A (en) * 1994-05-12 1998-03-24 Exxon Chemical Patents Inc. Liquid phthalic anhydride recovery process using a rectification tower
US5718808A (en) * 1996-11-29 1998-02-17 Exxon Chemical Patents Inc. Solvent assisted process for recovery of phthalic anhydride in the liquid phase by distillation
US5730844A (en) * 1996-11-29 1998-03-24 Exxon Chemical Patents Inc. Liquid phthalic anhydride recovery process using a rectification tower with benzoic acid control
US5869700A (en) * 1997-02-21 1999-02-09 Exxon Chemical Patents Inc. Method for recovering phthalic anhydride/maleic anhydride mixtures by distillation

Also Published As

Publication number Publication date
GB1121588A (en) 1968-07-31
BE680473A (enrdf_load_stackoverflow) 1966-10-17
DE1295540B (de) 1969-05-22
JPS548664B1 (enrdf_load_stackoverflow) 1979-04-17
CS150931B2 (enrdf_load_stackoverflow) 1973-09-17
NL6602053A (enrdf_load_stackoverflow) 1966-11-07

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